docs: add progress-bar component

[janhassel]

Adds documentation for Progress Bar component.

A couple notes:

• Currently (v7.41.0), the component has one accessibility violation which is tracked over in the main repo: fix(progress-bar): fix label accessibility violation carbon#9479. The accessibility docs refer a future version (7.42.0) in which this bug has been fixed and released, assuming that this documentation PR will take longer than the bug fix. This can obviously be changed if that's not the case.
• Live Demo is missing. I couldn't get it to work as docgen couldn't pick up the component. Perhaps this is due to the current unstable status of the component?

Changelog

New

• Adds documentation for the Progress Bar component

[vercel]

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🔍 Inspect: https://vercel.com/carbon-design-system/carbondesignsystem/e8X1G9ZkxySySo4yJgHKWs5ZSEMm
✅ Preview: https://carbondesignsystem-git-fork-janhass-a7b833-carbon-design-system.vercel.app

[dakahn]

unassigned myself on this, but happy to take a look if we pick the work back up again 👍🏾 🏄🏾

[janhassel]

Closing in favor of #2688